| 1. |
- Gopal, Vasanth, et al.
(författare)
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Performance of Hybrid Powder-Suspension Axial Plasma Sprayed Al2O3-YSZ Coatings in Bovine Serum Solution
- 2019
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Ingår i: Materials. - : MDPI AG. - 1996-1944. ; 12:12
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Tidskriftsartikel (refereegranskat)abstract
- Ceramic coatings on metallic implants are a promising alternative to conventional implants due to their ability to offer superior wear resistance. The present work investigates the sliding wear behavior under bovine serum solution and indentation crack growth resistance of four coatings, namely (1) conventional powder-derived alumina coating (Ap), (2) suspension-derived alumina coating (As), (3) composite Al2O3-20wt % Yittria stabilized Zirconia (YSZ) coating (AsYs) deposited using a mixed suspension, and (4) powder Al2O3-suspension YSZ hybrid composite coating ApYs developed by axial feeding plasma spraying, respectively. The indentation crack growth resistance of the hybrid coating was superior due to the inclusion of distributed fine YSZ particles along with coarser alumina splats. Enhanced wear resistance was observed for the powder derived Ap and the hybrid ApYs coatings, whereas the suspension sprayed As and AsYs coatings significantly deteriorated due to extensive pitting.
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| 2. |
- Hameed, Pearlin, et al.
(författare)
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Axial Suspension Plasma Spraying : An ultimate technique to tailor Ti6Al4V surface with HAp for orthopaedic applications
- 2019
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Ingår i: Colloids and Surfaces B. - : Elsevier BV. - 0927-7765 .- 1873-4367. ; 173, s. 806-815
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Tidskriftsartikel (refereegranskat)abstract
- Dissolution of atmospheric plasma sprayed (APS) hydroxyapatite (HAp) coatings on Ti-6Al-4 V medical implants have always been a challenge to overcome in the field of biomedical industry. In the present work, an attempt has been made to develop a HAp coating using a novel thermal spray process called axial suspension plasma spraying (SPS), which leads to thin adherent coatings. Two HAp coatings fabricated by APS (P1 and P2) and four SPS HAp coatings (S1, S2, S3 and S4) produced with varying spraying parameters were characterized in terms of (1) microstructure, porosity, hardness, adhesion strength, contact angle and phase purity; (2) corrosion resistance in 10% Fetal bovine serum (FBS); (3) in-vitro cell adherence and cell viability using human umbilical cord blood-derived mesenchymal stem cells (hMSCs). Amongst different APS and SPS coatings, P1 and S3 exhibited superior properties. S3 coating developed using SPS exhibited 1.3 times higher adhesion strength when compared to APS coating (P1) and 9.5 times higher corrosion resistance than P1. In addition, both S3 and P1 exhibited comparatively higher biocompatibility as evidenced by the presence of more than 92% viable hMSCs. © 2018 Elsevier B.V.
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| 3. |
- Khan, Pearlin Amaan, et al.
(författare)
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Influence of Graphene Nanoplatelets on the Performance of Axial Suspension Plasma-Sprayed Hydroxyapatite Coatings.
- 2022
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Ingår i: Bioengineering. - : MDPI. - 2306-5354. ; 10:1, s. -22
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Tidskriftsartikel (refereegranskat)abstract
- Axial suspension plasma spraying (ASPS) is an alternative technique to atmospheric plasma spraying (APS), which uses a suspension of much finer powders (<5-micron particle size) as the feedstock. It can produce more refined microstructures than APS for biomedical implants. This paper highlights the influence of incorporated graphene nanoplatelets (GNPs) on the behavior of ASPS hydroxyapatite (HAp) coatings. The characterization of the ASPS coatings (HAp + varying GNP contents) was carried out using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), confocal Raman microscopy (CRM), white light interferometry (WLI), and contact angle measurements. The evaluation of the mechanical properties such as the hardness, roughness, adhesion strength, and porosity was carried out, along with a fretting wear performance. Additionally, the biocompatibility of the Hap + GNP coatings was evaluated using cytotoxicity testing which revealed a decrease in the cell viability from 92.7% to 85.4%, with an increase in the GNP wt.%. The visualization of the cell's components was carried out using SEM and Laser Scanning Microscopy. Furthermore, the changes in the genetic expression of the various cellular markers were assessed to analyze the epigenetic changes in human mesenchymal stem cells. The gene expression changes suggested that GNPs upregulated the proliferation marker and downregulated the pluripotent markers by a minimum of three folds.
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| 4. |
- Pande, Ashwary, et al.
(författare)
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Influence of rate of heating to aging temperature on precipitation hardening in a metastable β titanium alloy
- 2014
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Ingår i: Advanced Materials Research. - : Trans Tech Publications. - 1022-6680 .- 1662-8985. ; 1025-1026, s. 445-450
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Tidskriftsartikel (refereegranskat)abstract
- A comparison between slow heating to aging temperature and direct charging at aging temperature on the microstructure and mechanical properties obtained after the aging was established for the metastable beta (β) titanium alloy Ti-15V-3Cr-3Al-3Sn. The alloy was subjected to two single aging (SA) and two duplex aging (DA) conditions, with two heating rates to aging temperature: (i) low heating rate of 5 oC/min (ii) direct charging into a furnace heated to aging temperature. The microstructure analysis was carried out using Field Emission Scanning Electron Microscopy. Mechanical Testing was carried to evaluate Ultimate Tensile Strength (UTS), 0.2% Yield Strength (YS), % Elongation (%El.), % Reduction in area (%RA) and hardness. In the case of SA samples aged at 500 °C for 8 h and 500 °C for 10 h, heating rate of 5 °C/min to aging temperature resulted in a finer microstructure but did not help in achieving better strength-ductility combination compared to direct charging. Lower rate of heating allows enough dwell time in the temperature range 250-300 oC for pre-precipitation reaction to occur which aids in fine scale precipitation of alpha phase during aging. In the case of DA samples aged at 250 oC for 24 h followed by 500 oC for 8 h and 300 oC for 10 h followed by 500 oC for 10 h, no tangible difference between lower rate of heating and direct charging was observed in mechanical properties or microstructure. This is believed to be due to the pre-aging steps 250 oC/24 h or 300 oC/10h in the two DA treatments, which create finely distributed precursors thereby leaving no scope for the heating rate to play a role.
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